diff --git a/devtools/session.py b/devtools/session.py
index c539dad2..3038c732 100644
--- a/devtools/session.py
+++ b/devtools/session.py
@@ -25,9 +25,11 @@ def send_command(self, command, params=None, cb=None):
         json_command = {
             "id": self.message_id,
             "method": command,
-            "params": params,
         }
 
+        if params:
+            json_command["params"] = params
+
         if self.session_id != "":
             json_command["session_id"] = self.session_id